Not really. He's 211cm. The trajectory of his serve is different from other players. And there's no chance of reacting to his serve (poor Djokovic), only reading and guessing. He easily hits 2nd serve aces, aswell.
Only point to practice ROS with him is preparing for a match against him or Isner.
It's a different kind of serve, Isner serve is more power oriented, while Karlovic can use power and accuracy.
You prerare better for Isner by practicing with Steve Johnson or Sam Querrey imho.
I'm pretty sure Karlovic doesn't serve at 100% in practice sessions, otherwise Popovic wouldn't even put the ball in play either. There is individual serving practice also for serving, so no need of serving like a real match in practice. The reason people don't like to practice with him it's not his serve, but his inability to mantain the ball in play I'd say.